The ecology of Sphyraena barracuda (Osteichthyes: Perciformes) in the Kosi system with notes on the Sphyraenidae of other Natal estuaries.

Abstract

Fry enter from the sea at a length of 20 mm and live in shallow marginal weed-beds until a length of 80 mm when they move to fringing reed-beds. After reaching 300 mm they move to open water areas. They attain 180 mm in the first 6 months and after 2 yr measure 400-500 mm. They leave the estuary after 2 yr. Their sigificance in the estuarine fish community is due to their predation, at all sizes, on a variety of estuarine-dependent juvenile fishes (eg. Rhabdosargus spp.) and adults of estuarine species (eg. Ambassis spp.). S. barracuda was recorded at salinities between 4per mille and 35per mille, only in very clear water and at temperatures from 14.4-37oC. Sphyraena bleekeri and S. qenie, also clear-water species, were found at Kosi in salinities from 0.5- 35per mille. Sphyraena jello is the most widespread barracuda in Natal estuaries, but only juveniles were recorded. This species is tolerant of a wide range of turbidities and salinities which enables it to live under most estuarine conditions. -from Author